Extractor hood

ABSTRACT

An extractor hood ( 10 ) for the separation of dirt particles, and especially fat and oil droplets from airflow is described. Extractor hood ( 10 ) includes a fan unit ( 18 ) for the creation of exhaust airflow through the extractor hood and a separator unit ( 20 ) to deposit dirt particles from the exhaust air flow. The separator unit ( 20 ) defines at least one air duct ( 25   a,    25   b ). Along the at least one air duct ( 25   a,    25   b ) an impact element ( 40 ) is arranged, featuring at least in certain areas capillary holes ( 44 ) for separating dirt particles through the capillary holes ( 44 ) along the at least one air duct ( 25   a,    25   b ).

FIELD OF INVENTION

The present invention concerns an extractor hood for the removal on dirt particles and especially fat and oil droplets from the airflow.

BACKGROUND OF INVENTION

Extractor hoods are especially deployed in kitchens to filter and remove cooking vapors above a stove or cooking area.

Generally extractor hoods are differentiated in two groups according to the type of airflow. In so-called exhaust air extraction hoods the exhaust air is channeled through ducting to the atmosphere outside the building, where the stove or cooking area is positioned to avoid smells and build-up of dirt within the kitchen and the building in general. In so-called air circulation extractor hoods the air absorbed by the extractor hood is cleaned by a filter and returned to the kitchen.

Conventional extractor hoods usually consist of a separator unit where the dirt particle separation occurs, and a fan or blower unit for removing the exhaust air. Separation can take place by means of separator elements and/or a suitable ducting of the airflow. In EP 1 502 057 for instance an extractor hood is described, in which by means of dual redirection of an airflow containing dirt particles the majority of the dirt particles is already deposited on the impact or separation surfaces.

Generally conventional extractor hoods contain a filter element between the first separation surface and the downstream fan unit, for instance a lint filter. Such lint filter consists of fine-woven fabric, which catches almost all remaining solid materials and dirt particles in the exhaust air before entering the fan unit. The higher the dirt particle concentration in the exhaust air, the faster the lint filter is saturated or blocked and can thus no longer fulfill its filter function. In this case the lint filter must be removed and cleaned or replaced with a new lint filter. It must also be considered that the lint filter presents a resistor within the flow system, which in comparison to an extractor hood without lint filter leads to a higher strain on the fan unit, meaning that the fan unit must produce a higher pressure difference. Higher strain on the fan unit inevitably leads to more operating noise, which can be annoying.

The task of this present invention is to create an extractor hood without aforementioned disadvantages.

SUMMARY OF INVENTION

The task is solved by an extractor hood according to claim 1. The extractor hood includes a fan unit to create exhaust airflow through the extractor hood and a separator unit for the separation of dirt particles from the exhaust airflow. The separator unit defines at least one air duct, in which the exhaust airflow is several times redirected. Here it is essential that along the at least one air duct one impact element is arranged, which at least in certain areas has capillary holes, so that dirt particles can be separated from the airflow through the capillary holes along the at least one air duct. These capillary holes are of a size to allow dirt particles deposited in the impact surface to be removed by the capillary effect from the impact surface. These dirt particles are no longer exposed to the exhaust airflow on the impact surface and can thus no longer be entrained by the exhaust airflow. Furthermore, the size of the capillary holes must be chosen in such way that the airflow cannot significantly pass through the impact surface. The diameter of the capillary holes is preferably in the range of 0.5 to 5 mm, and further preferably in the range of 1 to 3 mm.

According to another preferred design the separator unit is executed with two mirror-symmetric exhaust air ducts to a center line of the extractor hood, where the at least in certain areas arranged capillary holes in each of the exhaust air ducts have impact surfaces opposing and via a curved connecting area are joined sides of the impact element.

Further advantages of the invention and preferred designs arise from the following concrete description, characteristics and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred design of the invention is shown in the attached drawings.

FIGS. 1 a and 1 b show the front view and a cross section along line A-A of an extractor hood according to the invention.

FIGS. 2 a and 2 b show FIGS. 1 a and 1 b partly in exploded view.

FIG. 3 shows a perspective view of the extractor hood according to the invention partly in exploded view.

FIG. 4 shows parts of the separator unit of the extractor hood according to the invention as cross section in detail.

FIGS. 5 a and 5 b show parts of the separator unit of the extractor hood according to the invention in perspective view.

DETAILED DESCRIPTION OF A PREFERRED DESIGN

The invention is now explained in detail by means of a preferred design.

The attached Figures show extractor hood 10 as well as components of this extractor hood 10 according to the invention. Extractor hood 10 has a hollow cubic or shaft-like casing. Exemplary casing dimensions are: width 60 cm, depth 40 cm and height 80 cm. The casing consists mainly of a frame covered with stainless steel plates. On front 12 of this casing a detachable control knob 14, connected to the control unit (not shown) is attached, which allows the control of extractor hood 10 and especially its fan unit or blower 18. As can be seen in FIG. 3, extractor hood 10 shows, according the described design, also a suitable design of its top end 16, which allows for the extractor hood 10 to be ceiling-mounted above a stove, and which is provided with a circular opening to connect to an exhaust air duct. Although the extractor hood 10 described is designed as an exhaust hood, the expert can easily see that an extractor hood according to the invention can also be used in air circulation operation. Naturally, the extractor hood according to the invention 10 can also be wall-mounted instead of ceiling-mounted.

Within the casing of extractor hood 10 fan unit 18 and separator unit 20 are installed. As described in the following in more detail, during the operation of extractor hood 10 by means of fan unit 18 two exhaust airflows, in FIG. 4 schematically marked with dotted arrows, are maintained, which enter separator unit 20 by means of two longitudinal air inlets, front air inlet 22 a and rear air inlet 22 b, at the lower end of extractor hood 10 in separator unit 20, along two mirror-symmetric air ducts, front air duct 25 a and rear air duct 25 b, of separator unit 20 are lead through extractor hood 10 and exit at top end 16 of extractor hood 10. Separator unit 20 is designed in such way that within the respective airflows are redirected several times, so that dirt particles contained in the airflows, such as fat or oil droplets, are mainly deposited on the impact or separator surfaces of separator unit 20. The principle of at least dual airflow redirection in a separator unit is already known through aforementioned EP 1 502 057.

Aforementioned multiple redirection of the airflows in separator unit 20 of extractor hood 10 is mainly achieved by the shape and array of base element 30, impact element 40, central element 50 and ceiling element 60, which are part of separator unit 20. As can be seen especially in FIGS. 1 b and 4, the design of these elements 30, 40, 50 and 60 and thus also separator unit 20 assembled from these elements, are mainly symmetric with regard to a center line of extractor hood 10, which runs parallel to front 12, and in the cross section of FIG. 4 is shown as dotted center line B. In other words: the route through air duct 25 a defined by front section 20 a of separator unit 20 from front air inlet 22 a to fan unit 18 corresponds to the route of air duct 25 b defined by rear segment 20 b of separator unit 20 from rear air inlet 22 b to fan unit 18. By means of the following description the expert will detect that the invention can also be generally implemented in an extractor hood with only one air inlet with its separator unit only defining one air duct between this air inlet and a fan unit. Following the components of front section 20 a of separator unit 20 and/or elements 30, 40, 50 and 60 are marked with the additional letter a, while the segments of the rear segment of separator unit 20 and/or elements 30, 40, 50 and 60 are marked with the additional letter b.

Separator unit 20 consists, as already mentioned, mainly of base element 30, impact element 40, and central element 50 and ceiling element 60. As can be especially seen in cross section drawing FIG. 4, base element 30 has the shape of an oblong bowl with longitudinal reinforced front and rear outer rims 32 a, 32 b pointing upward, and a longitudinal central area 34, also pointing upward. Base element 30 is shaped in such way that between the outer rims 32 a, 32 b and central area 34 a front 36 a and rear bowl-like sections 36 b are formed. The central area 34 has along center line B a V-shaped depression 38, which is mainly complementary designed to lower end 42 of impact element 40, as described following in detail.

Front section 50 a and rear section 50 b of central element 50 are each designed in such way and positioned in relation to base element 30 that front section 50 a of central element 50 and front section 30 a of base element 30 together define the first section of front air duct 25 a, and that rear section 50 b of central element 50 and rear section 30 b of base element 30 together define the first section of rear air duct 25 b. As can be especially seen in the cross section drawing of FIG. 4, this can be for both front 50 a and rear sections 50 b of central element 50 a suitably curved metal sheet. Front section 50 a of central element 50 shows for instance an approx. 45 degree angle with respect to the horizontal upwards running flat section 52 a, an adjoining second section 54 a slightly running downward with respect to the horizontal, and adjoining third section 55 a, mainly running vertically down, an adjoining fourth section 56 a, mainly running horizontally, and an adjoining fifth flat section 58 a running preferably in a 70 degree angle upwards with respect to the horizontal. The rear section 50 b being symmetrical to front section 50 a of central element 50 shows the same first 52 b, second 54 b, third 55 b, fourth 56 b and fifth sections 58 b.

The shape of the respective first sections of air ducts 25 a, 25 b, which are defined by the shape and relative array of base element 30 and central element 50, can best be seen in the cross section drawing of FIG. 4. During extractor hood 10 operation from the stove ascending exhaust air containing dirt particles enter for instance through front air inlet 22 a, which is mainly defined by, with respect to the horizontal, approx. 45 degree upward running first flat section 52 a of front section 50 a of central element 50 and reinforced upward-pointing outer rim 32 a of front section 30 a of base element 30, in front area 20 a of separator unit 20. In air inlet 22 a entering exhaust air is for the first time redirected between the reinforced upward-pointing outer rim 32 a of front section 30 a of base element 30 and the slightly downward running second flat section 54 a and the adjoining, mainly vertically down running third flat section 55 a of front section 50 a of central element 50, since the airflow must follow the downwards curved air duct 25 a. Due to this first redirection of the airflow the majority of the dirt particles, such as fat and oil droplets, collect especially on the mainly vertically downward running third flat section 55 a of front section 50 a of central element 50. Such first redirection is in principle known from EP 1 502 057.

After the previously described first redirection the exhaust air flowing through the first section 20 a of separator unit 20 is redirected again due to the further shape of air duct 25 a, which is mainly defined by the front bowl-like section 36 a of base element 30 in the mainly horizontally running fourth flat section 56 a of central element 50. Due to the widening of air duct 25 a in this area the airflow is slowed. Again a part of the dirt particles, such as fat and oil droplets, which are still contained in the exhaust airflow, will deposit on the front bowl-like section 36 a of base element 30, especially in that part of front bowl-like section 36 a bordering central area 34 of base element 30.

As can be seen in the cross section drawing of FIG. 4, the further downstream part of air duct 25 a is formed by the preferably in an approx. 70 degree angle against the horizontal upward running fifth flat section 58 a of front section 50 a of central element 50 and front section 40 a of impact element 40. Impact element 40, according to the preferred design described here, shows in the cross section drawing of FIG. 4 mainly a U-shaped design with a flat front section 40 a, a curved connecting section 42, which forms the lower end of impact element 40, and a flat rear section 40 b. Impact element 40 can for instance be a suitably curved and mounted metal sheet. The curved connecting section 42 is designed in such way, that its shape, as shown in FIG. 4, is complementary to depression 38 in central area 34 of base element 30, and arranged in such way that the front bowl-like section 36 a of base element 30 virtually merges with front section 40 a of impact element 40. In other words: for the exhaust air flow the front bowl-like section 36 a of base element 30 and front section 40 a of impact element 40 virtually form a continuous surface.

As can be seen especially in FIGS. 2 a and 3 both front section 40 a and rear section 40 b of the impact element have a multitude of capillary holes 44. These capillary holes 44 are designed in such way that dirt particles, such as fat and oil droplets, which are still contained in the exhaust airflow, impact and adhere to front section 40 a and/or rear section 40 b of impact element 40, are removed due to the capillary effect and the continuous impact of airflow on the respective inner sides of front 40 a and/or rear section 40 b of impact element 40. The dirt particles removed in such way are no longer exposed to the exhaust airflows through the respective air ducts 25 a, 25 b and can therefore not be carried off by them. The capillary holes preferably have a diameter in the range of 0.5 to 5 mm, further preferably of 1 to 3 mm auf. Dirt particles, especially fat and oil droplets, removed on the respective inner sides of front 40 a and/or rear section 40 b of impact element 40, drain, due to gravitational force, on the inner sides of front 40 a and/or rear section 40 b of impact element 40 down and collect in the area of connecting section 42 of impact element 40. This connecting section 42 of impact element 40 can be shaped as a solid bowl, again provided with a multitude of capillary holes, or feature a different structure, which allows dirt particles collecting on the inner side of connecting section 42 to drip or drain off through V-shaped depression 38 defined by central area 34 of base element 40, such as a longitudinal slot.

After the previously described deposits of dirt particles contained in the airflow especially on the mainly vertically downward running third and fourth sections 55 a, 55 b of front 50 a and/or rear section 50 b of central element 50, on front 36 a and/or rear bowl-like section 36 b of base element 30 and front 40 a and/or rear section 40 b of impact element 40 the respective airflows through air ducts 25 a, 25 b are basically free of dirt particles. Any further dirt particles in the airflows through air ducts 25 a, 25 b are deposited due to two further redirections each, which are affected downstream of impact element 40. The flow direction through air duct 25 a is for instance downstream of impact element 40 twice nearly completely redirected, i.e. 180 degrees, by first a right hand bend and then a left hand bend by the design of front section 60 a of ceiling element 60 and its array in respect of front section 50 a of central element 50 and impact element 40. As described above the route of the airflow along air duct 25 b through rear section 20 b of separator unit 20 is mirror-symmetric to the previously described route of the airflow along air duct 25 a through front section 20 a of separator unit 20.

Ceiling element 60 consists mainly of a flat central section 62 with two side sections joining the side rims, running downward in an approx. 70 degree angle with respect to the horizontal, which are front side section 64 a and rear side section 64 b of ceiling element 60. As can be seen in the cross section drawing of FIG. 4, any residual deposits of dirt particles occur along the further route of air duct 25 a, where the greatest centrifugal forces occur, which is at the bottom of flat central section 62 and in an angle of approx. 70 degree with respect to the horizontal downwards running side section 64 a as well as along the part on top of air duct 25 a of, with respect to the horizontal, slightly downwards running second flat section 54 a of front section 50 a of central element 50. Further downstream the air flows, in this way cleaned of dirt particles, to fan unit 18, to be finally removed in circulation air or exhaust air operation.

Preferably the individual elements of separator unit 20, which are base element 30, impact element 40, central element 50 and ceiling element 60 are in such way installed inside extractor hood 10, that these elements can be easily removed and reinstalled for cleaning in extractor hood 10. Preferably base element 30, impact element 40, central element 50 and ceiling element 60 are made from a dishwasher-safe material, such as stainless steel, to be easily washed in a dishwasher in case of soiling for restoring the separation efficiency of separator unit 20. Especially base element 30, which will have to be cleaned most frequently, could be made of two telescopic metal sheets, so that the length of base element 30 can be adjusted to dishwasher dimensions. Separator unit 20 and its elements could be made removable by means of frictionally engaged connectors and/or magnets in extractor hood 10, as shown in FIGS. 5 a and 5 b.

As before described in detail, separator unit 20 of extractor hood 10 defines according to the preferable design of the invention two mirror-symmetric air ducts 25 a and 25 b with respect to center line B of separator unit 20. But as the expert will have detected, these two air ducts 25 a and 25 b are not running completely separate through separator unit 20. Especially in the area of impact element 40 the airflows through air ducts 25 a and 25 b interact beneficially. On the one hand the mutual impact of impact element 40 contributes, if selecting the suitable size of capillary holes 44, that the respective airflow cannot pass through impact element 40. On the other hand a certain gap can be left between V-shaped depression 38 in the central area 34 of base element 30 and the complementary shaped or curved connecting section 42 of impact element 40, since here the airflows from both sides meet and thus prevent continuous flow of further exhaust air in this area. In other words: for the respective exhaust airflows this gap between depression 38 in central area 34 of base element 30 and the complementary shaped connecting section 42 of impact element 40 to a certain degree virtually does not exist. The distance between the V-shaped depression 38 in the central area 34 of base element 30 and the curved connecting section 42 of impact element 40 is preferably in the range of 2 to 10 mm. Further preferred the distance is 5 mm.

Control knob 14 is preferably detachable and, like the elements of separator unit 20, made from a dishwasher-safe material. Control knob 14 of the preferred design of the invention of extractor hood 10 allows in connection with a control unit the control of fan unit 18, for instance the setting of different power levels, as well as the control of further electric components, such as lights. Preferably the setting of different power levels is affected by turning control knob 14 and switching the lights on and off by pressing control knob 14.

The preceding detailed description of the invention only serves as an explanation. The invention by no means is limited to the described design example, but can be adapted by an expert in a suitable way to individual operating requirements, which may deviate from the described operating conditions. The extractor hood according to the invention can for instance be favorably deployed in the industrial and commercial fields as well as in the non-commercial field. The expert will further detect that instead of the described symmetry the separator unit with regard to a section running parallel to the extractor hood front, such symmetry of the separator unit alternatively or in addition with regard to a vertical section of the extractor hood front through its center line can be achieved. It is further conceivable that the described separator unit shows a different geometry, for instance radial symmetric or elliptical. It is only essential that an air duct is formed by the separator unit, along which an impact element is arranged, which at least in certain areas has capillary holes to remove deposited dirt particles on the impact element.

The expert will further detect that the terms used, such as “front” and/or “rear”, “top” and/or “bottom”, “outer” and/or “inner”, etc. are not intended to limit the orientation of the described elements according to the invention, but only serve to differentiate these elements.

REFERENCE SIGN LIST

10 Extractor hood

12 Front

14 Control knob 16 Top end of extractor hood 18 Fan unit 20 Separator unit 20 a Front section of separator unit 20 b Rear section of separator unit 22 a Front air inlet 22 b Rear air inlet 25 a Front air duct 25 b Rear air duct 30 Base element 30 a Front section of base element 30 b Rear section of base element 32 a Front outer rim 32 b Rear outer rim 34 Central area 36 a Front bowl-like section 36 b Rear bowl-like section

38 Depression

40 Impact element 40 a Front section of impact element 40 b Rear section of impact element 42 Connecting section 44 Capillary holes 50 Central element 50 a Front section of central element 50 b Rear section of central element 52 a First section of front section of central element 52 b First section of rear section of central element 54 a Second section of front section of central element 54 b Second section of rear section of central element 55 a Third section of front section of central element 55 b Third section of rear section of central element 56 a Fourth section of front section of central element 56 b Fourth section of rear section of central element 58 a Fifth section of front section of central element 58 b Fifth section of rear section of central element 60 Ceiling element 60 a Front section of ceiling element 60 b Rear section of ceiling element 62 Central section 64 a Front side section of ceiling element 64 b Rear side section of ceiling element A Center line of section B Center line of separator unit 

1. Extractor hood (10) for separation of dirt particles and especially fat and oil droplets from airflow, including: a fan unit (18) to create an exhaust airflow through extractor hood (10); and a separator unit (20) to deposit dirt particles from the exhaust airflow; characterized by the separator unit (20) defining at least one air duct (25 a, 25 b), where along the at least one air duct (25 a, 25 b) an impact element (40) is arranged, which has at least in certain areas capillary holes (44) for separating dirt particles from the air flow along the at least one air duct (25 a, 25 b) through the capillary holes (44).
 2. Extractor hood (10) according to claim 1, where the impact element (40) in the at least one air duct (25 a, 25 b) is arranged in such way downstream from a redirection of the redirection flow that dirt particles, due to the centrifugal forces on the impact element (40), are deposited.
 3. Extractor hood (10) according to claim 1, where the capillary holes (44) have a diameter of approx. 0.5 to 5 mm.
 4. Extractor hood (10) according to claim 3, where the capillary holes (44) have a diameter in the range of approx. 1 to 3 mm.
 5. Extractor hood (10) according to claim 1, where the separator unit (20) defines a first air duct (25 a) and a second air duct (25 b), where the first air duct (25 a) with regard to a symmetry plane of the separator unit (20) is mirror-symmetric to the second air duct (25 a).
 6. Extractor hood (10) according to claim 5, where the impact element (40) is designed both along the first air duct (25 a) as well as along the second air duct (25 b).
 7. Extractor hood (10) according to claim 5, where the impact element (40) has a flat front section (40 a), a flat rear section (40 b) and a curved connecting section (42), which connects the flat front section (40 a) with the flat rear section (40 b).
 8. Extractor hood (10) according to claim 7, where the impact element (40) has a U-shaped profile, where the flat front section (40 a) runs mainly parallel to the flat rear section (40 b).
 9. Extractor hood (10) according to claim 7, where both the flat front section (40 a) as well as the flat rear section (40 b) of the impact element are provided with capillary holes.
 10. Extractor hood (10) according to claim 9, where the separator unit (20) further includes a base element (30), a central element (50) and a ceiling element (60), which define by their shape and relative array together with impact element (40) the first air duct (25 a) and the second air duct (25 b).
 11. Extractor hood (10) according to claim 10, where the first air duct (25 a) and the second air duct (25 b) are designed in such way that the airflow direction entering through the air inlets (22 a, 22 b) into the separator unit (20) is several times redirected to deposit dirt particles.
 12. Extractor hood (10) according to claim 11, where the impact element (40) above base element (30) is arranged in such way that between the curved connecting section (42) of impact element (40) and a complementary shaped depression (38) in a central area (34) of the base element a gap is formed.
 13. Extractor hood (10) according to claim 12, where the curved connecting section (42) of impact element (40) is designed in such way that dirt particles collecting on the inner side of connecting section (42) can drain off to the depression (38) defined by the central area (34) of base element (30).
 14. Extractor hood (10) according to claim 10, where base element (30), impact element (40), central element (50) and ceiling element (60) are designed to be removable from separator unit (20).
 15. Extractor hood (10) according to claim 1, where the extractor hood (10) further features a removable control knob (14), with which in connection with a control unit the fan unit power and light of the extractor hood (10) can be controlled.
 16. Extractor hood (10) according to claim 8, where both the flat front section (40 a) as well as the flat rear section (40 b) of the impact element are provided with capillary holes.
 17. Extractor hood (10) according to claim 16, where the separator unit (20) further includes a base element (30), a central element (50) and a ceiling element (60), which define by their shape and relative array together with impact element (40) the first air duct (25 a) and the second air duct (25 b).
 18. Extractor hood (10) according to claim 17, where the first air duct (25 a) and the second air duct (25 b) are designed in such way that the airflow direction entering through the air inlets (22 a, 22 b) into the separator unit (20) is several times redirected to deposit dirt particles.
 19. Extractor hood (10) according to claim 18, where the impact element (40) above base element (30) is arranged in such way that between the curved connecting section (42) of impact element (40) and a complementary shaped depression (38) in a central area (34) of the base element a gap is formed.
 20. Extractor hood (10) according to claim 19, where the curved connecting section (42) of impact element (40) is designed in such way that dirt particles collecting on the inner side of connecting section (42) can drain off to the depression (38) defined by the central area (34) of base element (30).
 21. Extractor hood (10) according to claim 17, where base element (30), impact element (40), central element (50) and ceiling element (60) are designed to be removable from separator unit (20). 